1. Field of the Invention
This invention relates to the control of disease in animals, especially poultry, through the use of novel bacteriocin-producing lactic acid-producing bacteria and/or novel bacteriocins produced by these species. It also relates to novel bacteriocins, amino acid sequences of the novel bacteriocins, and to the strains of lactic acid producing bacteria producing the novel bacteriocins. Furthermore, the invention relates to therapeutic compositions containing the novel bacteriocins and/or the strains of lactic acid producing bacteria producing them and to uses of the therapeutic compositions.
2. Description of the Related Art
The consumption of improperly prepared poultry products has resulted in human intestinal diseases. It has long been recognized that Salmonella spp. are causative agents of such diseases and more recently, Campylobacter spp., especially Campylobacter jejuni, has also been implicated. Both microorganisms may colonize poultry gastrointestinal tracts without any deleterious effects on the birds, and although some colonized birds can be detected, asymptomatic carriers can freely spread the microorganisms during production and processing, resulting in further contamination of both live birds and carcasses. Poultry serves as the primary reservoir for Salmonella and Campylobacter in the food supply (Jones et al., Journal of Food Protection, Volume 54, No. 7, 502-507, July, 1991). Prevention of colonization in live poultry during growout production may diminish the problem of poultry contamination.
A number of factors contribute to the colonization and continued presence of bacteria within the digestive tract of animals. These factors have been extensively reviewed by Savage (Progress in Food and Nutrition Science, Volume 7, 65-74, 1983). Included among these factors are: (1) Gastric acidity (Gilliland, Journal of Food Production, Volume 42, 164-167, 1979); (2) bile salts (Sharpe & Mattick, Milchwissenschaft, Volume 12, 348-349, 1967; Floch et al., American Journal of Clinical Nutrition, Volume 25, 1418-1426, 1972; Lewis & Gorbach, Archives of Internal Medicine, Volume 130, 545-549, 1972; Gilliland and Speck, Journal of Food Protection, Volume 40, 820-823, 1977); Hugdahl et al., Infection and Immunity, Volume 56, 1560-1566, 1988); (3) peristalsis; (4) digestive enzymes (Marmur, Journal of Molecular Biology, Volume 3, 208-218, 1961); (5) immune response; and (6) indigenous microorganisms and the antibacterial compounds which they produce. The first four factors are dependent on the phenotype of the host and may not be practically controllable variables. The immune response in the gastrointestinal (GI) tract is not easily modulated. The factors involving indigenous microorganisms and their metabolites are dependent on the normal flora of the GI tract.
One potential approach to control Campylobacter and/or Salmonella colonization is through the use of competitive exclusion (CE). Nurmi and Rantala (Nature, Volume 241, 210-211, 1973) demonstrated effective control of Salmonella infection by gavaging bacteria from healthy poultry intestinal materials into young chicks whose microflora had not yet been established, against Salmonella colonization. Administration of undefined CE preparations to chicks speeds the maturation of gut flora in newly-hatched birds and provides a substitute for the natural process of transmission of microflora from the adult hen to its offspring. Results from laboratory and field investigations provide evidence of benefits in Campylobacter control through administering normal microflora to chickens; decreased frequency of Campylobacter-infected flocks (Mulder and Bolder, IN: Colonization Control of human bacterial enteropathogens in poultry; L. C. Blankenship (ed.), Academic Press, San Diego, Calif., 359-363, 1991) and reduced levels of Campylobacter jejuni (C. jejuni) in the feces of colonized birds has been reported (Stern. Poultry Science, Volume 73, 402-407, 1994).
Schoeni and Wong (Appl. Environ. Microbiol., Volume 60, 1191-1197, 1994) reported a significant reduction in broiler colonization by C. jejuni through the application of carbohydrate supplements together with three identified antagonists: Citrobacter diversus 22, Klebsiella pneumoniae 23, and Escherichia coli 25. There is also evidence of a significant decrease of C. jejuni in intestinal samples from infected broilers after treatment with poultry-isolated cultures of Lactobacillus acidophilus and Streptococcus faecium (Morishita et al., Avian Diseases, Volume 41, 850-855, 1997).
Snoeyenbos et al. (U.S. Pat. No. 4,335,107, June, 1982) developed a competitive exclusion (CE) microflora technique for preventing Salmonella colonization by lyophilizing fecal droppings and culturing this preparation anaerobically. Mikola et al. (U.S. Pat. No. 4,657,762, April, 1987) used intestinal fecal and cecal contents as a source of CE microflora for preventing Salmonella colonization. Stem et al. (U.S. Pat. No. 5,451,400, September, 1995 and U.S. Pat. No. 6,241,335, April 2001) disclose a mucosal CE composition for protection of poultry and livestock against colonizations by Salmonella and Campylobacter where the mucin layer of prewashed caeca is scraped and the scrapings, kept in an oxygen-free environment, are cultured anaerobically. Nisbet et al. (U.S. Pat. No. 5,478,557, December, 1996) disclose a defined probiotic that can be obtained from a variety of domestic animals which is obtained by continuous culture of a batch culture produced directly from fecal droppings, cecal and/or large intestine contents of the adult target animal.
Microorganisms produce a variety of compounds which demonstrate anti-bacterial properties. One group of these compounds, the bacteriocins, consists of bactericidal proteins with a mechanism of action similar to ionophore antibiotics. Bacteriocins are often active against species which are closely related to the producer. Their widespread occurrence in bacterial species isolated from complex microbial communities such as the intestinal tract, the oral or other epithelial surfaces, suggests that bacteriocins may have a regulatory role in terms of population dynamics within bacterial ecosystems. Bacteriocins are defined as compounds produced by bacteria that have a biologically active protein moiety and bactericidal action (Tagg et al., Bacteriological Reviews, Volume 40, 722-256, 1976). Other characteristics may include: (1) a narrow inhibitory spectrum of activity centered about closely related species; (2) attachment to specific cell receptors; and (3) plasmid-borne genetic determinants of bacteriocin production and of host cell bacteriocin immunity. Incompletely defined antagonistic substances have been termed “bacteriocin-like substances”. Some bacteriocins effective against Gram-positive bacteria, in contrast to Gram-negative bacteria, have wider spectrum of activity. It has been suggested that the term bacteriocin, when used to describe inhibitory agents produced by Gram-positive bacteria, should meet the minimum criteria of (1) being a peptide and (2) possessing bactericidal activity (Tagg et al., supra).
Lactic acid bacteria are among the most important probiotic microorganisms. They are Gram-positive, nonsporing, catalase-negative organisms devoid of cytochromes. They are anaerobic but are aerotolerant, fastidious, acid-tolerant, and strictly fermentative with lactic acid as the major end-product of sugar fermentation. Lactic acid producing bacteria include Lactobacillus species, Bifidobacterium species, Enterococcus faecalis, Enterococcus faecium, Lactococcus lactis, Leuconostoc mesenteroides, Pediococcus acidilactici, Sporolactobacillus inulinus, Streptococcus thermophilus, etc. These species are of particular interest in terms of widespread occurrence of bacteriocins within the group and are also in wide use throughout the fermented dairy, food and meat processing industries. Their role in the preservation and flavour characteristics of foods has been well documented. Most of the bacteriocins produced by this group are active only against other lactic acid bacteria, but several display anti-bacterial activity towards more phylogenetically distant Gram-positive bacteria and, under certain conditions, Gram-negative bacteria.
Lactobacilli have been extensively studied for production of antagonists. These include the well characterized bacteriocins (DeKlerk, 1967; Upreti and Hinsdill 1975; Barefoot and Klaenhammer 1983; Joerger and Klaenhammer 1986); potential bacteriocin-like substances (Vincent et al., 1959), and other antagonists not necessarily related to bacteriocins (Vakil and Shahni 1965; Hamdan and Mikolajcik 1974; Mikolajcik and Hamdan 1975; and Shahni et al., 1976).
Klaenhammer (1993) has classified the lactic acid bacteria bacteriocins known to date into four major groups:
Class I—Lantibiotics which are small peptides of <5 kDa containing the unusual amino acids lanthionine and β-methyl lanthionine. These are of particular interest in that they have very broad spectra of activity relative to other bacteriocins. Examples include Nisin, Nisin Z, carnocin U 149, lacticin 481, and lactocin 5.Class II—Small non-lanthionine containing peptides: a heterogeneous group of small peptides of <10 kDa. This group includes peptides active against Listeria spp.Class III—Large heat labile proteins >30 kDa. An example is Helveticin.Class IV—Complex bacteriocins-proteins containing additional moieties such as lipids and carbohydrates.
The present invention provides novel compositions containing at least one novel strain of a lactic acid-producing bacterial strain and/or novel bacteriocins produced by the at least one novel strain; a method of using the strain or bacteriocin, the novel strains, amino acid sequences for the novel bacteriocins, and methods of use, all of which are different from related art strains, bacteriocins, and methods of using.